Electronic article surveillance devices such as security tags or labels are placed on products to prevent theft. These devices are often used in retail stores. An activated security tag is placed on an item to sound an alarm at the store exit if the security tag is not deactivated. No alarm will sound if the tag is properly deactivated at the store cash register after the customer has purchased the appropriate item.
The security tag basically comprises a resonator strip mounted loosely to permit movement in a plastic housing. A magnetic bias strip is attached outside this housing and is covered with a plastic layer. When the bias strip is magnetized, it will cause the security tag to be active. The security tag is deactivated by demagnetizing the bias strip.
With the bias strip of the security tag magnetized, the resonator can receive a signal from a transmitter to absorb energy from the transmitter. When the transmitter stops transmitting, the resonator strip vibrates because of its proximity to the magnetized bias strip to transmit its own signal at a set frequency. This signal from the vibrating resonator strip can be picked up by a receiver to set off the alarm. If the bias strip is demagnetized, the resonator strip will not transmit its own signal at the set frequency to set off the alarm.
Conventionally, the security tags are made by cutting plastic styrene sheets and placing the cut sheets in a forming mold. Heat is applied to the sheet while a vacuum pressure pulls the plastic into the mold to conform the sheet to the mold to form housing cavities. Resonator strips cut to length at another manufacturing location or production line are placed in the formed housing cavities. Clear plastic lid stock is cut to shape and placed over the formed styrene sheet to close the cavities with the resonator strips inside. The lid stock and styrene layers are then joined by heat sealing. The bias strips or magnets are then placed on the outer surfaces of the lid stock and secured by an adhesive layer.
In a separate production line, the sheet can be cut into individual labels with the waste material being removed. Additionally, an activation field can be provided to activate the tags. Automatic and manual testing can also be performed in downstream processing.
This conventional manufacturing system cannot be made fully automatic and does not permit use of a single production line to make a finally manufactured security tag. The required operator assistance, coordination of separate production lines and the movement of the respective parts between the separate production lines increases the cost of manufacture and slows production.